LaFAYETTE, Ga. - When Joshua Michael Fowler came home Saturday night, something seemed wrong, his wife said. He seemed paranoid. He kept looking out the window, kept waiting for somebody.

At 11 p.m., the guests arrived at the Fowlers' home on Davenport Lane.

Investigators with the Walker County Sheriff's Office and the Georgia Bureau of Investigation said they needed to talk to Joshua Fowler about his grandmother, 75-year-old Joyce Ann Fowler, who police found on her bed, beaten to death. Neighbors told investigators that they saw Joshua at her Chickamauga home around 9 a.m. Saturday, the time when a crime scene specialist believes she died.

He seemed restless, fidgety. Eventually, police say, he admitted to using cocaine and methamphetamine, and officers arrested him on charges of violating parole. But they also brought him in as the lead suspect in the slaying of his grandmother.

Behind the house, behind a deck and a trampoline, near a shed, investigators found Joshua Fowler's 2005 Chevrolet Tahoe. And inside, they found splotches of blood, almost everywhere. Blood on the door. Blood on some clothes. Blood on the seats and the console and the steering wheel.

Investigators didn't know whose blood it was, still don't. But they believe it's Joyce Fowler's, and on Monday afternoon the Walker County Sheriff's Office charged 30-year-old Joshua Fowler with murder. He has not admitted to the crime, and police don't understand the motive. They think he may have killed her for money, or pills.

Amber Fowler is trying to figure out what happened, too. She said her husband had no violent history.

"Josh, he lost his way," she said. "He has a good heart. He's a really good person. He was, at one point, a good father, a good husband. This is a classic example of what drugs will do to a person. I love him. I will always love him. We have a little boy and ...

I don't know."

During a news conference Monday afternoon, Walker County Sheriff Steve Wilson said investigators will continue to put together the pieces.

"We feel certain we have the person responsible," Wilson said.

Nobody answered when a reporter showed up at Joyce Fowler's home on Mimosa Drive on Monday afternoon. Next door, a man stopped mowing his lawn to reflect on Joyce, his neighbor of 38 years.

Like many people on his street, James McGregor said, Joyce was private, but kind. She owned her own business, and her husband, Robert, participated in rescue missions for the Walker County Emergency Management Agency. After Robert died in December 2012, Joyce lived alone, mostly.

Joshua Fowler was released from Walker State Prison in October after a 17-month stint for possession of cocaine, possession of marijuana and obtaining a controlled substance. He then began to live with Joyce "off and on," according to police.

McGregor, 70, said Joshua Fowler first moved in with his grandparents as a child when his own parents divorced. Both he and Wilson, who also knew Joyce and Robert Fowler, say the grandparents looked after Joshua, even during times of trouble.

"This boy's been in and out of trouble at least twice, that I know of," the sheriff said. "They would always come and try to get him out, give him money. ... They were his biggest advocate."

On Saturday evening, one neighbor told McGregor that she was worried about Joyce. So McGregor and others approached the house.

"We knocked and knocked," he said.

Nobody answered. When neighbors looked through the window, McGregor said, they saw that someone had cut Joyce Fowler's phone lines.

They called 911. Walker County Deputy Christopher Gravitt arrived and walked inside through an open back door. After searching the house, he found a collection of empty pill bottles and Joyce Fowler, lying across her bed.

Someone had beaten her in the back left part of her head. The weapon lay next to the bed. Citing "the integrity of the investigation," Wilson won't say what weapon the killer used, but the GBI crime lab is processing it for fingerprints. That could take 2-4 months.